pid_delta_dalitz.C

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// pi- + d -> Delta0 + n -> n + n + pgamma* -> n + n + e- + e+
// This macro tests:
//   1. The beam momentum sampling
//   2. The deuteron Fermi sampling
//   3. The mass-dependent width Breit-Wigner distribution of the Delta 
//   4. The dilepton mass for Delta Dalitz decay
 
{
    gROOT->Reset();
    
    PParticle *p1 = new PParticle("pi-", 0, 0, 1.3);  // projectile   = 1.3 GeV/c
    PParticle *p2 = new PParticle("d");               // target
    PParticle *p3 = new PParticle("n");
    PParticle *delta = new PParticle("D0");
    
    PParticle *p4 = new PParticle("n");
    PParticle *dl = new PParticle("dilepton");
    
    PParticle *em = new PParticle("e-");
    PParticle *ep = new PParticle("e+");
    
    PParticle *q = new PParticle(*p1 + *p2);   // composite pi-+d
    
    PParticle *s1[] = {q, delta, p3};
    PParticle *s2[] = {delta, p4, dl};
    PParticle *s3[] = {dl, em, ep};
    
    PChannel *c1 = new PChannel(s1);
    PChannel *c2 = new PChannel(s2);
    PChannel *c3 = new PChannel(s3);
    PChannel *cc[] = {c1, c2, c3};
    
    PReaction *r = new PReaction(cc, "pid_delta_dalitz", 3, 1);
    
    r->Print();
    r->loop(100000);
}